Electronic organ diode keying circuit



I-larold 0. Schwartz North Tonawanda;

[72] Inventors Filed Patented Assignee Appl. No.

William v, Machanian, Niagara Fall; Robert D. Barry, Lockport, New York 726,872 May 6, 1968 Dec. 1, 1970 The Wurlitzer Company Chicago, Illinois a corporation of Delaware ELECTRONIC ORGAN DIODE KEYING CIRCUIT 4/1966 Milho 10/1968 Tinker 12/1968 Kramer Primary Examinerl-lerman Karl Saalbach Assistant Examiner-Timothy Vezeau Attorney-0lson, Trexler, Wolters & Bushnell 84/ l .26 84/1 .26X 84/1 .26X 84/1 .26X

ABSTRACT: A two-manual electronic organ wherein continually oscillating tone generators are respectively switched 13 Claims 3 Drawing Figs to output or utilization circuits through diodes which are nor- [52] 11.8. CI 84/].26, mally biased for nonconduction. Each key has only one single- 84/124 pole single-throw switch which acts through a diode to turn on [51] Int. Cl. G10h l/02 a switching transistor, which transistor in turn turns on the ap- [50] Field of Search 84/1 .01, propriate diode to key the output. Various stops are conl.22, 1.23, 1.24, 1.26 trolled through diodes.

m A G'EIVEAATDKS 54 .56 I l/ KEY a 57m? DIODE F/z. rc/r s flMPz HER I WWI/E5 SWITCHES SWITCHES 50 56 f'oo 7146 E 5779p SLLSTA/N SW/RL'HES ELECTRONIC ORGAN DIODE KEYING CIRCUIT Heretofore it has been common practice in the electronic organ arts to use a plurality of switch contacts controlled by each key. Such switch contacts may transmit the audio signal, or they may switch potentials which are used in one manner or another to key the audio signals. Direct keying of audio signals often results in undesired keying noises. In any event, large numbers of key contacts controlled by a single key result in problems of sequencing. Even though all contacts are supposed to make and break at the same time, wear of parts and bending of switch contacts may cause some of the contacts to open or close before others. In any event, make and break contacts are always a weak point, and trouble may be expected from oxidation, arcing, etc., although this can be somewhatimproved by the use of very expensive materials.

Accordingly, it is an object of the present invention to provide an electronic organ where there is only one single-pole single-throw switch for each key.

It is another object of the present invention to provide an electronic organ wherein a combination of transistors and diodes is used for keying each note.

More specifically, it is an object of this invention to provide an electronic organ wherein the electric oscillations corresponding to each note are either blocked or conveyed by a diode, and wherein a transistor is used to turn each diode on and off.

It is yet another object of the present invention to provide an electronic organ wherein diodes are used for controlling various stops of the organ.

Other and further objects and advantages of the present invention will be apparent from the following description when taken in connection with the accompanying drawings wherein:

FIG. 1 is a perspective view of an organ constructed in accordance with the present invention;

FIG. 2 is a block diagram of an organ construction in accordance with the present invention;.and

FIG. 3 is a partial schematic wiring diagram of the organ.

Turning now in greater particularity to the drawings, and first to FIG. 1, there will be seen an organ l constructed in accordance with the principles of the present invention. The organ may be or the spinet type, having shortened, overlapping manuals or keyboards, and one octave plus one of pedals, or it may have longer, full keyboards, and a full 32'- note pedalboard. In any event, the organ includes an upper or swell manual or keyboard 12, and a lower or great manual or keyboard 14, as well as a plurality of stop tablets 16. The organ further includes a pedal manual or clavier 18 and a swell pedal 20 for controlling the overall volume of the organ. A suitable loudspeaker system 22 is disposed behind grille cloth at the front of the organ, and this may include one or more loudspeakers.

The switching of the organ will be understood generally from FIG. 2, wherein the generators are indicated collectively at 24. The generators may be of any suitable type known and used for electronic organs, but at the present state of technology, such generators preferably are transistor oscillators. The organ in question is of the subtractive or formant type as opposed to the additive or synthesizing organ. The generators are connected to diode switches or keying circuits 26, the latter including diodes respectively connected to the generators and normally biased for nonconduction, but rendered conductive by closure of key switches as hereinafter set forth. Sustain is connected to'certain of the diode switches as indicated at 28.

The diode switches are controlled by transistor switches 30, and the transistor switches are in turn connected to key switches 32 which control the operation thereof. A positive voltage is connected to the key switches as indicated at 34. Stop switches 36 are connected from between the key switches 32 and transistor switches 30 to ground.

The output from the diode switches 26 is connected to filters 38 which maybe of known type, and the output from the filters is connected to an amplifier 40, which may include preamplifier stages and the power amplifier. The output of the amplifier is connected to the loudspeaker system 22 previously noted, and this preferably comprises a plurality of speakers in accordance with known audio principles.

The lower manual key switches are shown in FIG. 3 The number of switches depends on the number of keys, and for a complete organ there will be 6l keys per manual and a corresponding 61 key switches 32. As noted heretofore, there is only one key switch 32 per key. Each key switch comprises a single fixed contact 42, and all of the fixed contacts are connected to a positive voltage supply bus 44 which is connected to the positive voltage source 34. Each key switch further includes a plurality of movable contacts 46. The broken line 48 in FIG. 3 indicates the large number of switches 32 to avoid inclusion of unnecessary detail in the drawings, and it will be understood that each movable contact 46 is individually movable by any suitably mechanical connection or mechanism to the respective key.

Each movable key contact 46 is connected to a corresponding bus 50. It will be understood that there is one such bus 50 for each key contact, and that it is connected to only one key contact. A plurality of resistors 52 is connected to each bus 50. The number of resistors depends on the number of footage stops connected to a particular key, and for purposes of discussion, the resistors are hereinafter identified as 52-l, 52- 2, 52-3, through 52-n. By way of explanation, the resistors go to various footage stops, and on to various additional complex or flute stops, and for each key contact there may be a maximum of l l resistors. By way of example, there could be flute stops at 16, 8, 5%, 4, 2%, 2', and 1', with complex stops at 16, 8', 4', and 2.

Each resistor 52 on the side opposite the bus 50 is connected to a junction 54. Each junction 54 leads through a diode 56 to a common bus 58. This bus is engageable by a movable switch arm 60 connected to ground in order to ground the bus, each movable switch arm 60 and bus 58 comprising one of the footage stop switches 36. By way of example, all notes corresponding to an 8 complex stop would be connected to the bus 58-1 through the various diodes 56-1 (only some of which are shown). With the switch 60-1 closed on the corresponding bus 58-1, the bus would be retained at ground potential and the corresponding stop would be off, since potential applied from the source 34 through the diode 56-] would simply go to ground. By way of example, the footage stop switch 36-1 might comprise an 8' complex stop, while the footage stop switch 36-2 might comprise a 4' complex stop. Others will be apparent to those skilled in the art from the listing of footages set forth shortly above.

Each junction 54 is connected to a diode 62, appropriate numeral suffixes again being applied. In each instance it is the anode of the diode 56 or 62 that is connected to the junction 54. The cathode of each diode 62 is connected to a junction 64, and each junction 64 has a collector 66 connected thereto with a plurality of diodes 62 from other key switches connected thereto. These will be from key switches having a particular footage relation to the key switch for which the complete wiring is shown.

Each junction 64 is connected by a wire 68 to the base of a switching transistor 70. The collector of this transistor is connected to a positive potential bus wire 72 leading to a positive voltage source 74. The base is grounded through a shunting capacitor 76 and resistor 78, and the output is taken from the emitter as indicated at 80. As will be seen, the transistor is of the NPN type. The emitter further is connected to a resistor 82 leading to a junction 84. The junction 84 is grounded through a capacitor 86 and shunting resistor 88, the capacitor comprising a sustain capacitor. The junction 84 also is connected to a resistor 90 leading to the anode of a diode 92. The cathode of the diode 92 is connected to a common connection 94 which is connected to a normally open switch 56. Upon closure of the switch 96 the resistor 50 is connected in parallel with resistor 88 more quickly to discharge the capacitor 86, and thus to produce a short sustain.

There is a transistor70 corresponding to each key and key switch of the lower manual. The emitter output at 80 is connected to a resistor 98 in each instance, and this leadsto a junction 100. The junction is shunted to ground by capacitor 102, and is connected to the anode of a diode104 leading to a junction 106. The junction 106 leads to the anode of a diode 108, the cathode thereof being'connected to a resistor 110. The resistor 110 is, in turn, connected to a junction 112, and

this junction is connected to a tone generator 114 comprising one of the tone generators collectively numbered 24.

The junction 100 further is connected through a capacitor 116 to a junction 118, and-this junction leads through a re sistor 120 to the melodia output, and through a resistor 122 to the complex output. The melodia and complex outputs include the filters 38 and suitable stop switches for connecting the filters to produce the various melodia and complex tones, which are in turn connected to the amplifier andto the speaker system,

Normally the diodes 104 and 108 are biased off. Thus, no tone signal gets through from the generator 114 to the melodia and complex outputs. in this connection it will be understood that the tone signal may be of any suitable type, but in the preferred example it is square wave varying between zero and a positive value. When any of the lower manual key switches 32 is closed-for example, the one connected to the resistor 52-1-the're is a tendency to bias on each of the diodes 62. Whichever of the diodes 62 is connected to a footage stop switch 36 which is open is biased on, the others remaining nonconductive due to the shunting ofthe potential to ground by the corresponding diode ordiodes 56. Each diode 62 that is biased on (biased for conduction) applies'a positive voltage to the base of the corresponding transistor 70, thereby. biasing on that transistor and the transistor in turn biasing on the corresponding diodes 104 and 108, whereby the generator signal is passed to the melodia and complex outputs. During conduction of a diode'70, the corresponding capacitor 86 is charged. When the key switch is opened, the corresponding diodes 104 and 108 continue to conduct at a decreasing: level as the capacitor 86 corresponding thereto discharges through the corresponding resistor 88. In addition, if the .shortsustain switch 96 is closed, discharge of the capacitor 86 is hastened through the corresponding resistor 90 and diode 92.

Thus, each transistor 70 not only servesas a switch to turn on the corresponding diodes to conduct the generated signal,

but each also acts as a current sourcefor the corresponding switching diodes 104 and 108 so that there is no robbing regardless of the number of notes played simultaneously. Furthermore, the sustain is independent of the number of notes played. t

The upper manual key switches controlled by the upper manual keys 14 are not shown in FIG. 3. However, they will be understood to be similar to those shown for. the lower manual, and to be connected in the same manner, each toa transistor 124 connected in the same manner as the ,transistor 70, .with an emitter output connected through a resistor 126 to a junction 128. The junction 128 is connected to the anode of a diode 130, the cathode of which is connected to the junction 106. Thus, theid igdes 108 and 130 are in series, and the diode 108 is shared by the upper and lower manuals, being in series with either the diode 104 or the diode l3 0, or both. The junc- The junction 144 also is connected through a rather low value resistor 150 to the anode of a diode 152, the cathode of which is also connected to the sustain circuit 148.

The sustain circuit 148 includes a shortsustain switch 154 including a movable switch arm 156 normally engageable with a fixed switch contact 158 and movable into engagement with a second fixed contact 160. The first fixed contact 158 is connected to a ground line 162, while the second fixed contact 160 is connected to a low positive voltage line.

The medium sustain switch 164 includes a pair of ganged movable switch arms, namely an upper arm 166 and a lower arm 168. The upper arm 166 is connected as by a wire 170 to the movable short sustain switch arm 156. The upper switch arm 166 normally engages a first fixed contact 172, and is movable away therefrom into engagement with nothing. The lower movable switch'arm 168 normally engages an upper fixed contact 174, and is movable away therefrom into engagement with'a lower fixed contact 176. The upper fixed contact 174 is connected to a high negative voltage line 178, while the lower fixed contact 176 is connected through a re sistor 180 to the high negativevoltage line 178.

The long sustain switch 182 includes an upper movable switch arm 184 and a lower movable switch arm 186, the two being ganged together. The upper arm 184 is connected as by a wire 188 to the upper medium sustain fixed contact 172. The upper long sustain switch arm 184 normally engages a fixed contact 190 which is connected by a wire 192 to the cathode of diode 152. The arm 184 is movable out of engagement with the'fixed contact 190 and into engagement with nothing. The

5 emitter'capacitor thereof charges to a positive potential.

' When the transistor 124 then is biased for nonconduction, and

' with the three sustain switches in the position shown, there is a rather low resistance'discharge path through the resistor 150 and diode 152, through wire 192 to fixed contact 190, through movable switcharm"184 and wire 188 to fixed contact 172 and movable switch arm 166, and through wire 170 to movable switch arm 156 and fixed contact 158 to ground. Thus, the emitter capacitor discharges almost instantaneously. When the short sustain switch is operated, the arm 156 is connected to a ow positive voltage, and hence the emitter capacitor discharges quickly, but not quite so quickly as with no sustain V at all on.

When the medium sustain switch is operated, the circuit to the switch arm 156 is opened completely as the arm 166 moves away from the fixed contact 172. However, there is a rather high resistance'path from the'emitter' capacitor through the resistor 146 and wire 198 to themovable switch arm 186 'and fixed contact 194, and from there through the wire 196 andimovabl'e switch am 168 to the fixed contact 176, and

thence throughlhe resistor to the high negative voltage line 178, thus'producing a somewhat slower discharge of the emitter capacitor.

When the long sustain switch is operated, the resistor 146 andwire 198 are connected through the movable switch arm 186 and fixed switch contact 200 direct to ground, thus producing a somewhat longer discharge time for the capacitor than when the, connection was to the high negative voltage.

I Flute stops are provided on both the upper and lower manuals. Thus, one of the resistors 52, etc., of each of the upper and lower manual switches is a flute stop of a particular footage, andleads to a transistor 202. As will be understood, there are other similar switching transistors, one for each flute stop for each note. Except for having two connections to its base input, the transistor 202 is connected in the same manner as the transistor 70, output being taken from the emitter through a resistor 204 to a junction 206. The junction 206 is connected to the anode of a diode 208, the cathode thereof being connected to a shunting capacitor 210 and to the anode of a diode 212. The cathode of the diode 212 is connected through a resistor 214 to the junction in leading to the generator 114. The two diodes 208 and 212 are simultaneously turned on when the transistor 202 is biased for conduction, and the two diodes in series produce more isolation that would a single diode. The various capacitors behind the various diodes, such as capacitors 1 02, 107, 132, and 210, serve to shape the waves passed by the diodes to a certain extent.

The junction 206 also is connected to the anode of a diode 216 leading to a resistor-218 to the flute output. Six junctions 206 are connected to each flute filter, and the diodes 216 pro- OPERATION Somewhat in summary of what has been said before, upon closure of one of the lower manual key switches 32, potential will be applied to.the corresponding line 50 and to the various resistors 52. For each of the n footage stop switches 36 that is closed, the potential will'be shortened to ground. However, for each one that is in open or playing condition, the potential will be passed on by the corresponding diode 62 to the corresponding switching transistor 70. As will be appreciated, since the line 66 provides for a plurality of connections, the diodes 62 prevent interaction and false signalling.

Whichever transistor 70 is turned on, also turns on the corresponding diodes 104 and 108, whereby the signal is carried from the generator 114 to the melodia and complex outputs.

Assuming that one of the flute stops is also on, potential will be applied to the appropriate transistor 202 to turnit on, and thus also to turn on the'diodes 208, 212, and 216 to transmit the signal from the generator 114 to the flute filters. Operation of the upper manual key switches is identical to turn on a respective upper manual switching transistor 124, and thus to turn on the appropriate diodes l30 and 108 to transmit the signal from the generator to the upper manual melodia and complex outputs, and also to the flute output as just described in the event that a flute footage stop is open.

The specific example of the invention as herein shown and described is for illustrative purposes only. Various changes in structure will no doubt occur to those skilled in the art, and will be understood as forming a part of the present invention insofar as they fall within the spirit and scope of the appended claims.

lclaim:

l. in an electric organ comprising a keyboard having a plurality of playing keys, a plurality of key switch means corresponding to said keys, each of said key switch means comprising a single-pole single-throw switch, normally open and closed by depression of a respective key, a plurality of to tone generators corresponding to the notes of said organ and each providing a corresponding electric oscillation, and an output system; a keying system comprising apotential source of predetermined polarity, means connecting said potential source to said switches, a plurality of normally nonconducting diodes respectively connected to said switches on the side opposite said potential source and individually rendered conductive upon closure of a respective switch, a plurality of normally nonconducting transistors respectively connected to said diodes and individually rendered conductive upon con duction of a respective diode, a plurality of normally nonconducting diode means respectively connected between said tone generators and said output system, and means respectively connecting said transistors to said diode means'to render said diode means individually conductive upon conduction of a a respective transistor and thereby to transmit a correspond including a potential source connected to said transistor, the emitter of each transistor being connected to corresponding diode means.

3. A keying system as set forth in claim 2 and further including a plurality of sustain capacitors respectively connected to the emitters of said transistors, and variable means for discharging said capacitors to produce a variable sustain.

4. A keying system as set forth in claim 1 and further including an additional plurality of diodes respectively connecting a necting a plurality of key switches to said common-connec tion, and means for selectively connecting said common connection back to said potential source to shunt said potential and thereby to leave said first-mentioned diodes nonconducting upon closure of the respective key switches.

6. A keying system as set forth in claim 5 and further including a plurality of common connections corresponding to different predetermined footage stops, groups of said plurality of additional diodes respectively connecting a plurality of said key switches to said common connections, and means for individually and selectively connecting said common connections back to said potential source to shunt potential and conducting upon closure of key switches.

7. in an electronic organ comprising a keyboard having a plurality of playing keys, a plurality of key switch means corresponding to said keys, each of said key switch means comprising a singe-pole single-throw switch, normally open and closed by depression of a respective key, a plurality of tone generators corresponding to the notes of said organ and each providing a corresponding electric oscillation, and an output system; a keying system comprising a potential source to said switches, a plurality of normally nonconducting transistors, means respectively connecting said key switches to said transistors for rendering selected transistors conductive upon closure of corresponding key switches, a plurality of normally nonconducting diode means respectively connected between said tone generators and said output system, and means respectively connecting said transistors to said diode means to render said diode means individually conductive upon conduction of a respective transistor and thereby to transmit a corresponding electric oscillation from a corresponding tone generator to said output system.

8. A keying system as set forth in claim 7 and further including a potential source connected to said transistors each transistor having an emitter, a base, and a collector, the emitter of each transistor being connected to the corresponding diode means in an emitter-follower output.

9. In an electric organ comprising a keyboard having a plurality of playing keys, a plurality of key switch means corresponding to said keys, each of said key switch means comprising a single-pole single-throw switch, normally open and closed by depression of a respective key, a plurality of tone generators corresponding to the notes of said organ and each providing a corresponding electric oscillation, and an output system; a plurality of normally nonconducting electronic switch means respectively interconnecting said generators and said output system, said electronic switch means having a respective plurality of control input connections, a plurality of normally nonconducting diodes, there being one such diode connected between each key switch and said control input connection, and a plurality of additional diodes connecting groups of footage related key switches to predetermined ones of said control input means.

10. A keying system as set forth in claim 9 and further including a common connection corresponding to a predetermined footage stop, a plurality of further diode means respectively connecting a plurality of key switches to said common connection, and means including a stop switch for selectively connecting said common connection back to said potential source to shunt potential and thereby to leave the first-mentioned diodes nonconducting upon closure of corresponding key switches. I v

11. A keying system as set forth in claim and further including a plurality of common connections; groups of said further diodes respectively connecting key switches to said common connections, and individual means for selectively connecting said common connections back to said potential source to shunt potential and thereby to leave certain of said first-mentioned diodes nonconducting upon closure of key switches.

12. In an electric organ comprising a keyboard having a plurality of playing keys, a plurality ofkey switch means corresponding to said keys, each of said key switch means comprising a single-pole single-throw switch, normally open and closed by depression of a respective key, a plurality of tone generators corresponding to the notes of said organ and each providing a corresponding electric oscillation, and an output system; a keying system comprising a potential source of predetermined polarity, means connecting said potential source to said key switches, a plurality of normally nonconducting electronic switches respectively interconnecting said generators andsaid output system and each having a control input connection, a plurality of diodes respectively connecting said key switches to said control input connections, a common connection corresponding to apredetermined footage stop, a plurality of further diodes respectively connecting a plurality of key switches to said common connection, and means ineluding a stop switch for selectively connecting said common connection back to said potential source to shunt potential and thereby to leave certain of saidfirst-mentioned diodes nonconducting upon closure of corresponding key switches.

13. A keying system as set forth in claim 12 and further including a pluralityof common connections, groups of said plurality of further diodes connecting key switches to said common connections, and means for including stop switches for selectively respectively connecting said co'mmonconnect ions back to said potential source to shunt potential and thereby to leave certain of said first-mentioned diodes nonconducting upon closure of key, switches.

Patent No.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Decemb er L, l2ZD Inventor(s) Harold O. Schwartz William V. Machanian and Robert D. Barry It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 1, line 36, change "construction" to --constructed Column 1,

Column 2,

Column 2,

Column 2,

Column 3,

Column Column Column Column 5,

line

line

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change "or to --of-;

4, after "switches" insert --32--;

change "shortened" to --shorted--; and

after "plurality of" omit --to-- Signed and sealed this 29th day of June 1971.

(SEAL) Atte s't:

EDWARD I"I.FLETCHER,JR.

Attesting Officer WILLIAM E. SCHUYLER, Commissioner of Pate 

